The discoverer of the infrared rays, Sir Frederick William Herschel was born in Hanover, Germany in 1738. He was well known both as a musician and astronomer. In the year 1757 he immigrated to England where his daughter Carolina built a telescope. His most famous discovery was of the planet Uranus in year 1781. In the year 1800, Sir William Herschel made another important discovery.
He was interested in verifying how much heat passed through filters of different colors when kept in the sunlight. He realized that those of different color filters let pass different levels of heat. Continuing with this experiment, Herschel passed sunlight by a prism of glass and it formed a spectrum (the rainbow that forms when sunlight is divided into its different colors).
Making temperature controls in different colors in the spectrum, he observed that beyond the visible red radiation, the temperature was higher. He found that the invisible radiation beyond the red light behaves the same way from the standpoint of reflection, refraction, absorption and visible light transmission. It was the first time someone showed that there was another form of illumination or radiation that is invisible to the naked eye. This was called radiation heat initially and then called Infrared Rays (infra: means below) is below the energy of red wavelength.
The year 2000 marked the 200th anniversary of William Herschel's discovery of infrared and infrared technology is booming in all its applications. Astronomy, medicine, public safety, rescue, in electronics, in meteorology, process engineering, industrial maintenance, analysis of vegetation, the study of ocean temperatures to name a few. Not only is it booming, but also emerging as a technology for mass use in the medium term.
Expanding terms, heat transfer is energy in transit due to temperature differences. Heat is an intangible thing. We can not measure heat directly. We can only measure the effects of heat, namely, changes in temperature. Heat transfer can be by conduction, convection, radiation or combinations thereof. The speed (the difference generates contrast) of heating or cooling depends on the thermal properties, physical condition, size and nature of the product, as well as the transfer mechanism. Infrared thermography is used to obtain the energy radiated in the infrared range (0.7 to 15 microns), by the body temperature transmitter.
Infrared thermography or the use of thermal cameras requires professionals to assess the three forms of heat transfer. Thermography is not simply the generation of an image with a thermal camera / infrared. The technique of image generation and evaluation of it should be considered as a heat test. Despite the convenience and reliability of the thermo cameras, their use is not too widespread.